After five preseason games, and with only two remaining, the malfunctioning exists not with the reserves but with the starting unit.

In back-to-back preseason games – first against the Boston Celtics and then Wednesday night against the Toronto Raptors – coach Doug Collins’ first team found itself down 12 points midway through the third quarter.

In both cases, the energy and competitiveness of the second unit charged a comeback.

The Sixers, 1-4 in the preseason, eventually defeated the Celtics, but lost in double overtime to the Raptors.

The team’s late-game turnarounds are uplifting in the preseason, something heartening to reference.

But when the regular season begins, the team’s backups won’t be facing opponents experimenting with lineups and sets.

The Sixers did not practice on Thursday. They return to the Philadelphia College of Osteopathic Medicine on Friday, facing four days of practice before Tuesday’s preseason game against the Cavaliers in Cleveland.

“That’s what I have to take a look at,” said Collins, referring to his first team’s troubles. “I’m a big first-quarter guy. . . . Look what a team’s winning percentages are when you win the first quarter.”

On Wednesday, Collins allowed his starters to play without offensive sets. He gave them a set of basic rules, but did not impose a playbook because he felt it had been detrimental.

“I work 12 to 14 hours a day trying to find the best things I can do,” Collins said.

As Wednesday’s game wore on and the starters looked lackluster and predictable, Collins kept a mix of guys – his starting backcourt with high-energy reserves – on the court through the fourth quarter and both overtimes.

“At the end of the day, I told the guys the will to compete on a nightly basis will help you win games in this league,” Collins said.

“And I think that’s been the hardest thing. I think they’ve picked and chose spots to compete in the past. And we just can’t do that. We don’t have enough talent to do that.”

Point guard Jrue Holiday, who posted a triple-double against the Raptors, played 45 minutes and finally looked like the future star this franchise believes he will be.”